Rotary compressors are well known devices, used in several fields to develop a pressure gradient between two points across a stream of working gases. Two main types of rotary compressors are in use, dynamic compressors, i.e., centrifugal flowing, axial flowing, and the combined types, and positive displacement compressors. In dynamic compressors the working gases are accelerated followed by its deceleration within diverging passages, wherein part of its kinetic energy is converted into static pressure rise. In positive displacement compressors the pressure is increased by reducing the specific volume of the gases during their passage through the compressor.
Dynamic Compressors are widely in use in gas turbine and steam engines as they are able to raise the pressure of a relatively large volume of working gases while operating at relatively high rotational speeds. On the contrary, conventional types of positive displacement rotary compressors are not convenient for use in gas turbine engines, and the like, as the friction between the rubbing parts within them limits their practically useful range of operating rotational speeds.
Prior art, which is not relied upon, includes U.S. Pat. No. 4,227,868 by Nishikawa et al., U.S. Pat. No. 4,278,399 by Erickson, U.S. Pat. No. 4,358,244 by Nishikawa et al., U.S. Pat. No. 6,739,835 by Kim, Japan Pat. No. JP354013002A, Japan Pat. No. JP35508794A, and German Pat. No. DE3243169A1. Each of them showing a compressor impeller having a first disk and a second disk and a plurality of vanes arranged there between.